package com.slt.concurrency.mashibing2019.juc.c_005_AtomicXXX;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.LongAdder;

/**
 * 测试 cas 与 sync 的效率对比
 * <p>
 * LongAdder ： 在并发特别高时候，效率比较高
 * 分段锁原理
 */
public class T02_AtomicVsSyncVsLongAdder {
    static long count2 = 0L;
    static AtomicLong count1 = new AtomicLong(0L);
    static LongAdder count3 = new LongAdder();

    static void microSleep(int m) {
        try {
            TimeUnit.MICROSECONDS.sleep(m);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws Exception {
        Thread[] threads = new Thread[1000];

        for (int i = 0; i < threads.length; i++) {
            threads[i] =
                    new Thread(() -> {
                        for (int k = 0; k < 100000; k++) count1.incrementAndGet();
                    });
        }

        long start = System.currentTimeMillis();
        for (Thread t : threads) t.start();
        for (Thread t : threads) t.join();
        long end = System.currentTimeMillis();
        System.out.println("Atomic: " + count1.get() + " time " + (end - start));


        //synchronized-----------------------------------------------------------
        Object lock = new Object();
        for (int i = 0; i < threads.length; i++) {
            threads[i] = new Thread(() -> {
                for (int k = 0; k < 100000; k++)
                    synchronized (lock) {
                        count2++;
                    }
            });
        }
        start = System.currentTimeMillis();
        for (Thread t : threads) t.start();
        for (Thread t : threads) t.join();
        end = System.currentTimeMillis();
        System.out.println("Sync: " + count2 + " time " + (end - start));


        //LongAdder----------------------------------
        for (int i = 0; i < threads.length; i++) {
            threads[i] =
                    new Thread(() -> {
                        for (int k = 0; k < 100000; k++) count3.increment();
                    });
        }
        start = System.currentTimeMillis();
        for (Thread t : threads) t.start();
        for (Thread t : threads) t.join();
        end = System.currentTimeMillis();
        System.out.println("LongAdder: " + count1.longValue() + " time " + (end - start));

    }

}
